I bought a dyson battery 1 year ago, mainly because their site shows an image of their 'superior batteries' against the cheap knock-offs found on eBay and Amazon.
One year later the battery failed, which leads me to believe there's no difference between the poor quality batteries and espare batteries, only that at least you know what you're getting when you buy a cheap battery.
I emailed espares for a replacement or refund with the order number, part number and all other relevant info. They replied asking for the model of dyson I had, which was odd, seeing as the part number and order confirmation email had clearly shown the compatibility. I sent it, and they told me that the part had failed because it was 'incompatible', which was doubly odd seeing as it was sold as an OEM battery for the exact dyson it had been used in, clearly specified on their website.
I then received an email saying they were processing a refund and I should wait 5 - 7 days. After 7 working days I contacted them to ask where my refund was. They told me there had been a problem with the refund but I should wait 5 - 7 days for a refund. 7 working days later I emailed to ask where my refund was and they asked for my PayPal address. I gave it and they said it would take another 5 - 7 days to refund.
I think any reasonable person would feel fobbed off at this point without any real expectation that they are honestly attempting to issue a refund.
So in summary: I bought an expensive, poor quality battery. They keep promising a refund and giving poor excuses for delays.
If this review is not updated, that means I still have not received a refund. I will however update this if they do, stating how long it actually took.
Make of this what you will.